Sound Card with External DAC

I see. Then I suspect that these transports doesn't maintain the purity of the signal, i.e. they manipulate the signal somehow.

I really want to see some strong argument that a bit is more than just a bit. In the analog world, we know how more expensive gears manipulate the signal to sound "expensive" with all the filters along the way. In the digital world, unless then data is manipulated, then it will remain exactly as what recorded on the CD.

I'm not questioning "high-quality" audio since my point is stressing that the digital data read by CDROM is as pure as what is on the CD. We all know that pure data doesn't necessarily sounds good, as well as expensive speakers never have real flat response. My point is audio signal purity, which comes from data integrity kept in a computer.

I sold my california audio labs transport/DAC pair, and am using my CDROM and my computer as the audio source. The signal is kept in digital from the CDROM till it gets out from the computer box, and converted to analog by the Stereo-link 20-bit DAC (CD audio is 16-bit).

I would never turn back.

Guys, what's wrong here is that "CD-audio data is read correctly in digital by CDROM drives". It's correct for audio extraction with CRC check, multiple re-reads, and error handling, but not for playing CD in CDROM drive. When you play audio CD real-time, the received audio data will almost never be 100% lossless. In this case much better built CDP or Transport easely outperfom any CDROM. But if you do audio an extraction from CDROM to hard drive using EAC and Plextor or another very good drive, that HDD may become a perfect source.

data is data, audio or other data (word document, software, etc), they are all data.

If you say you can't rely on CDROMs to read audio data, then you also can't rely on the CDROM to read the Microsoft Office installation CD that you paid $700 for it. I don't know. Does not make any sense to me.

If I may make an analogy Boogie, if that were the case, symphonies would only hire Musicians who can read music well and would care less about the ability to actually play the instruments.

"Reading" the Data is merely the tip of the iceberg.

Data IS data, but the way how they read it are different. I would suggest you to read some FAQs about 'how cd-player works'. Shortly, when you read data CD, your drive works on, let's say, 24x speed with buffering, it has enough time to read, check CRC, and re-read if necessary up to several times. And re-tries ARE necessary, due to the nature of CD media. When you play an audio CD, your drive (except Meridians?) has only one attempt for anything, obviously no CRC check performed. The result is not 100% accurate data retrieved, resulting in jitter, which directly affects sound quality.
On the other hand, audio extraction (from CD to HDD with appropriate software: with CRC, re-reads, variable speeds, etc.) is much closer to the way how data CDs are processed, and thus a perfect copy may be obtained.